[cfe-commits] r111283 - in /cfe/trunk: lib/Analysis/CFG.cpp test/Analysis/dead-stores.c

[Ted Kremenek]

Author: kremenek
Date: Tue Aug 17 16:00:06 2010
New Revision: 111283

URL: http://llvm.org/viewvc/llvm-project?rev=111283&view=rev
Log:
Fix horrible CFG bug caused by a series of NullStmts appearing at the beginning of a do...while loop.  This would cause
the body of the DoStmt to be disconnected from the preceding code.

Modified:
    cfe/trunk/lib/Analysis/CFG.cpp
    cfe/trunk/test/Analysis/dead-stores.c

Modified: cfe/trunk/lib/Analysis/CFG.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/CFG.cpp?rev=111283&r1=111282&r2=111283&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/CFG.cpp (original)
+++ cfe/trunk/lib/Analysis/CFG.cpp Tue Aug 17 16:00:06 2010
@@ -702,7 +702,10 @@
 
   for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend();
        I != E; ++I ) {
-    LastBlock = addStmt(*I);
+    // If we hit a segment of code just containing ';' (NullStmts), we can
+    // get a null block back.  In such cases, just use the LastBlock
+    if (CFGBlock *newBlock = addStmt(*I))
+      LastBlock = newBlock;
 
     if (badCFG)
       return NULL;

Modified: cfe/trunk/test/Analysis/dead-stores.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Analysis/dead-stores.c?rev=111283&r1=111282&r2=111283&view=diff
==============================================================================
--- cfe/trunk/test/Analysis/dead-stores.c (original)
+++ cfe/trunk/test/Analysis/dead-stores.c Tue Aug 17 16:00:06 2010
@@ -462,3 +462,27 @@
   }
 }
 
+// <rdar://problem/8320674> NullStmts followed by do...while() can lead to disconnected CFG
+//
+// This previously caused bogus dead-stores warnings because the body of the first do...while was
+// disconnected from the entry of the function.
+typedef struct { float r; float i; } s_rdar8320674;
+typedef struct { s_rdar8320674 x[1]; } s2_rdar8320674;
+
+void rdar8320674(s_rdar8320674 *z, unsigned y, s2_rdar8320674 *st, int m)
+{
+    s_rdar8320674 * z2;
+    s_rdar8320674 * tw1 = st->x;
+    s_rdar8320674 t;
+    z2 = z + m;
+    do{
+        ; ;
+        do{ (t).r = (*z2).r*(*tw1).r - (*z2).i*(*tw1).i; (t).i = (*z2).r*(*tw1).i + (*z2).i*(*tw1).r; }while(0);
+        tw1 += y;
+        do { (*z2).r=(*z).r-(t).r; (*z2).i=(*z).i-(t).i; }while(0);
+        do { (*z).r += (t).r; (*z).i += (t).i; }while(0);
+        ++z2;
+        ++z;
+    }while (--m);
+}
+